In March 1661 Henry Jermyn, Earl of St. Albans, who had an interest in the area as one of the trustees holding the bailiwick on behalf of the Queen Mother, Henrietta Maria, was granted a lease of the bailiwick until 1691. In the following month he granted leases, mostly for about twenty-one years, of the 220 or so houses already built.

It was St. Albans who was responsible for the creation of the greater part of the street-pattern east of St. James's Street. This was facilitated when in September 1662 his leasehold interest was extended to 1720 and in the 1670's further extensions were made until 1740. In the meantime, however, he had obtained, on 1 April 1665, the very valuable and important grant of the freehold of about half the field, including the site of St. James's Square.

Thus from late in 1662 the term of St. Albans's tenure was sufficiently long to give an incentive to develop the whole area of St. James's Field with new streets as well as to complete the frontages towards the surrounding streets. In 1663 his building-activities were being commented on, and in that year the market place was established for his new residential faubourg. The new leases he was granting were longer than the old, running for forty-five to fifty years, and by the time his 'rent-roll' came to be made up in 1676 (ref. 5) it could record an income from his leasehold and freehold property in this area of some £4120 per annum. His greatest profit was not, however, recorded, and it is therefore not known for what sum he had sold off parts of his freehold estate, including the very valuable sites facing St. James's Square.

The post-Restoration development of the area as a whole took some twenty years to complete. The impulses from St. Albans's extended lease of 1662 and freehold grant of 1665 were checked by the natural and political calamities that followed, and it was not until the early 1670's that the chief work was going forward, with the realization of St. Albans's plans for the square and the surrounding streets. In the later 1670's and early 1680's the church of St. James was being built, and it was at about the same time that the development by other speculators of the area westward of St. James's Street was taken in hand.

The development of an area so close to St. James's Palace was certain to be an object of royal interest, and a number of the street-names celebrated the royal family (others commemorated St. Albans's own family, and one, Bury Street, perhaps his Suffolk home). The great square seems to have been known at one time as the 'Place Royale'. The Crown's officers were certainly concerned to some extent in the development. A certain stylistic resemblance between the houses in the square and the back part of old Schomberg House suggests that some architectural influence may have affected alike development on the Crown estate and on St. Albans's freehold.